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In a certain solar house, energy from the Sun is stored in barrels filled with water. In a particular winter stretch of five cloudy days, \(1.00 \times 10^{6}\) kcal is needed to maintain the inside of the house at \(22.0^{\circ} \mathrm{C}\). Assuming that the water in the barrels is at \(50.0^{\circ} \mathrm{C}\) and that the water has a density of \(1.00 \times 10^{3} \mathrm{~kg} / \mathrm{m}^{3},\) what volume of water is required?

Short Answer

Expert verified
The required volume of water is approximately 35.714 m³.

Step by step solution

01

Understand the Concept of Heat Transfer

The problem involves calculating the amount of heat transfer required to maintain the house temperature using water. Since we know the initial and final temperatures, we can use the formula \(Q = mc\Delta T\) where \(Q\) is the heat energy, \(m\) is the mass of the water, \(c\) is the specific heat capacity of water, and \(\Delta T\) is the change in temperature.
02

Calculate the Mass of Water Required

Rearrange the equation \(m = \frac{Q}{c\Delta T}\) to solve for \(m\). The specific heat capacity of water \(c\) is \(1.00 \, \text{kcal/kg}^\circ\text{C}\). We have \(Q = 1.00 \times 10^6 \, \text{kcal}\). The temperature change \(\Delta T = 50.0^\circ\text{C} - 22.0^\circ\text{C} = 28.0^\circ\text{C}\). Thus:
03

Perform the Calculation for Mass

Substitute the known values into the formula: \[ m = \frac{1.00 \times 10^6}{1.00 \times 28.0} = \frac{1.00 \times 10^6}{28.0} \text{ kg} \] This results in \(m = 35714.29 \, \text{kg}\).
04

Calculate the Volume of Water Required

Given the density of water is \(1.00 \times 10^3 \, \text{kg/m}^3\), we use the formula \(\text{Volume} = \frac{\text{Mass}}{\text{Density}}\). So:\[ \text{Volume} = \frac{35714.29}{1.00 \times 10^3} \text{ m}^3 \]This gives us a volume of \(35.714 \, \text{m}^3\).
05

Conclusion

The volume of water required to maintain the house temperature over the five cloudy days is approximately \(35.714 \, \text{m}^3\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Specific Heat Capacity
Specific heat capacity is an essential concept in heat transfer processes. It determines how much heat energy a substance can absorb for a given increase in temperature. For water, this property is particularly significant since it is a common material used for thermal storage due to its high specific heat capacity compared to many other substances.
  • Specific Heat Capacity (\( c \) for water) is the amount of heat required to raise the temperature of one kilogram of the substance by 1°C.
  • For water, this value is typically \( 1.00 ext{ kcal/kg}^ ext{°C} \).
This means that water can store or release a substantial amount of energy as it cools or heats, making it highly efficient for applications in thermal storage such as storing solar energy in solar houses. Understanding how this property affects calculations allows one to estimate the amount of energy a given mass of water can store when changing temperature.
Change in Temperature
The change in temperature is an important parameter when calculating the amount of heat absorbed or released in any process involving thermal energy. In terms of the problem described, the difference between the initial temperature of the water and the temperature to which it will cool provides the temperature change (\( \Delta T \)).
  • In our scenario, the initial temperature (\( T_i \)) is 50°C, and the final desired temperature (\( T_f \)) is 22°C.
  • The change in temperature calculation is \( \Delta T = T_i - T_f \).
  • Hence, \( \Delta T = 50 - 22 = 28^ ext{°C} \).
This change in temperature is pivotal to determining the mass of water needed because it impacts the total heat energy that the water will release during the cooling process. Smaller temperature changes would mean less energy is stored or released, implying the need for either more or less water to achieve the same energy effect, respectively.
Volume Calculation
After determining the required mass of water through the heat transfer equation, the next step is to relate this mass to volume using the density of water. This conversion is crucial since volume is often a more practical measure for storage purposes, especially in contexts like solar energy storage.
  • Volume calculation uses the formula: \( \text{Volume} = \frac{\text{Mass}}{\text{Density}} \).
  • Given the density of water is \( 1.00 \times 10^3 \, \text{kg/m}^3 \), it allows us to directly convert the mass of water into volume.
  • So, with a calculated mass of 35714.29 kg, the volume is \[ \text{Volume} = \frac{35714.29}{1.00 \times 10^3} \] which equals approximately 35.714 m³.
Utilizing the density for this calculation simplifies the conversion from mass to volume, especially for substances like water where density is well-known and constant under standard conditions.

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Most popular questions from this chapter

In the extrusion of cold chocolate from a tube, work is done on the chocolate by the pressure applied by a ram forcing the chocolate through the tube. The work per unit mass of extruded chocolate is equal to \(p / \rho,\) where \(p\) is the difference between the applied pressure and the pressure where the chocolate emerges from the tube, and \(\rho\) is the density of the chocolate. Rather than increasing the temperature of the chocolate, this work melts cocoa fats in the chocolate. These fats have a heat of fusion of \(150 \mathrm{~kJ} / \mathrm{kg} .\) Assume that all of the work goes into that melting and that these fats make up \(30 \%\) of the chocolate's mass. What percentage of the fats melt during the extrusion if \(p=5.5 \mathrm{MPa}\) and \(\rho=1200 \mathrm{~kg} / \mathrm{m}^{3} ?\)

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A cube of edge length \(6.0 \times 10^{-6} \mathrm{~m}\) emissivity \(0.75,\) and temperature \(-100^{\circ} \mathrm{C}\) floats in an environment at \(-150^{\circ} \mathrm{C}\). What is the cube's net thermal radiation transfer rate?

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